U.S. patent application number 12/857971 was filed with the patent office on 2011-02-24 for system and method for drm content management.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Kyu-Hui HAN, Kwan-Hyuk IM.
Application Number | 20110047080 12/857971 |
Document ID | / |
Family ID | 43416679 |
Filed Date | 2011-02-24 |
United States Patent
Application |
20110047080 |
Kind Code |
A1 |
IM; Kwan-Hyuk ; et
al. |
February 24, 2011 |
SYSTEM AND METHOD FOR DRM CONTENT MANAGEMENT
Abstract
A system for managing a Digital Rights Management (DRM) content
includes a content providing server for providing an environment,
through which a DRM content and a digital right of the DRM content
can be registered, a service providing server for issuing a license
serving as a usage authority for each of DRM content files provided
from the content providing server, generating a license revocation
execution value in a specific field of the issued license,
encrypting the generated license revocation execution value for
transmission to a user terminal, and the user terminal for
inspecting the license of the DRM content file transmitted from the
service providing server, and extracting and storing the license
and the license revocation execution value to use a corresponding
DRM content file according to the license, and upon receiving a
revocation request, transmitting a revocation result of the
corresponding license to the service providing server.
Inventors: |
IM; Kwan-Hyuk;
(Gyeongsangbuk-do, KR) ; HAN; Kyu-Hui; (Daegu,
KR) |
Correspondence
Address: |
Cha & Reiter, LLC
17 Arcadian Avenue, Suite 208
Paramus
NJ
07652
US
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Gyeonggi-Do
KR
|
Family ID: |
43416679 |
Appl. No.: |
12/857971 |
Filed: |
August 17, 2010 |
Current U.S.
Class: |
705/59 ; 705/1.1;
726/26 |
Current CPC
Class: |
G06F 21/10 20130101;
G06F 2221/0777 20130101 |
Class at
Publication: |
705/59 ; 705/1.1;
726/26 |
International
Class: |
G06Q 10/00 20060101
G06Q010/00; H04L 9/28 20060101 H04L009/28; G06F 21/00 20060101
G06F021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 18, 2009 |
KR |
10-2009-0076439 |
Claims
1. A system for managing a Digital Rights Management (DRM),
comprising: a content providing server for providing a plurality of
DRM contents and retrieving a license; a service providing server
for issuing a license serving as a usage authority for each of DRM
content files provided from the content providing server,
generating a license revocation execution value in a specific field
of the issued license, encrypting the generated license revocation
execution value; and a user terminal for inspecting the license of
the DRM content file transmitted from the service providing server,
and extracting and storing the license and the encrypted license
revocation execution value to use a corresponding DRM content file,
and upon receiving a revocation request, transmitting a revocation
result of the corresponding license to the service providing
server.
2. The system as claimed in claim 1, wherein when the usage
authority of the DRM content file has expired, the service
providing server transmits a license revocation request list to the
user terminal to revoke the license issued for the corresponding
DRM content file, the license revocation request list including a
license ID for each of the DRM content files corresponding to the
expired usage authority with a revocation execution code key value
for decrypting the encrypted generated revocation execution
value.
3. The system as claimed in claim 1, wherein the revocation result
of the corresponding license of the user terminal corresponds to
one of (1) decrypting of the encrypted licensed revocation
execution value of the DRM content file using a revocation
execution code key value provided in a revocation license list
received from the service providing server, and in response,
transmitting the revocation code value serving as decryption result
information together with the corresponding revoked license ID and
(2) refusing a license revocation for the corresponding DRM content
file.
4. The system as claimed in claim 1, wherein upon receipt of the
revocation result from the service providing server, granting, by
the content providing server, an advantage of recall, refund, or
usage term extension for the DRM content file corresponding to the
revoked license.
5. The system as claimed in claim 1, wherein the user terminal
periodically checks a corresponding license of each of the DRM
content file, and when the usage authority of the DRM content file
has expired as a result of the check, the user terminal transmits a
license re-issuance request message of the corresponding DRM
content file to the service providing server.
6. The system as claimed in claim 1, wherein upon receiving a
license re-issuance request message of specific DRM content file
from the user terminal, the service providing server transmitting a
corresponding license ID and a revocation execution code key value
to the user terminal to re-issues the license of the specific DRM
content file.
7. A method for managing a DRM content, the method comprising:
registering, by a content providing server, a DRM content and a
digital right of the DRM content; issuing, by a service providing
server, a license serving as a usage authority for each of DRM
content files, generating a license revocation execution value in a
specific field of the issued license, encryption the generated
license revocation execution value, and transmitting the encrypted
license revocation execution value; inspecting, by a terminal, a
transmitted DRM content file, and extracting and storing the
license and the encrypted license revocation execution value; when
the usage authority of the DRM content file has expired, generating
and transmitting a license revocation request list including a
license ID of a corresponding DRM content file matched with a
license revocation code value; and decrypting the encrypted license
revocation execution value of the corresponding DRM content file by
using the revocation code value obtained through the received
license revocation request list, and transmitting a revocation
execution code key value serving as decryption result
information.
8. The method as claimed in claim 7, further comprising granting an
advantage of recall, refund, or usage term extension for the
corresponding DRM content file to the terminal that has transmitted
the decryption result information.
9. The method as claimed in claim 7, further comprising:
periodically checking, by the terminal, a corresponding license of
each of the DRM content files, and when a usage authority of the
DRM content file has expired as a result of the checking,
transmitting a license re-issuance request message of corresponding
DRM content file to the service providing server; and when the
service providing server has received the license re-issuance
request message for specific DRM content file, transmitting a
corresponding license ID and another revocation code value to the
terminal through the license revocation request list and re-issuing
the license of the specific DRM content file.
Description
CLAIM OF PRIORITY
[0001] This application claims priority under 35 U.S.C.
.sctn.119(a) to a Korean Patent Application entitled "System and
Method for DRM Content Management" filed in the Korean Intellectual
Property Office on Aug. 18, 2009 and assigned Serial No.
10-2009-0076439, the contents of which are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a system and a method for
Digital Rights Management (DRM). More particularly, the present
invention relates to a DRM system and a DRM method for providing
service to a reliable user through authentication, so that it is
possible to more safely protect the rights of a provider and a user
of DRM contents.
[0004] 2. Description of the Related Art
[0005] Digital Rights Management (hereinafter referred to as "DRM")
technology refers to technology for managing and protecting
intellectual property rights of digital content using an encryption
scheme. That is, the DRM technology is used for securely providing
a user with various contents from a Content Provider (CP) and
preventing unauthorized usage and distribution of the contents.
Such DRM technology can protect information through generation,
distribution, and usage until abandonment of the digital contents.
It also protects the usage and right according to the user's
authority in an office as well as on online environment.
[0006] In order to use the contents applied with the DRM technology
in a portable terminal, first, the user of a portable terminal must
access the content, then a server provides the corresponding DRM
content and download the DRM content, meta data corresponding to
the DRM content, and a license. Here, the license includes
information indicating the usage authority of the contents (e.g.
the allowed number of usage s and term).
[0007] When the DRM content and the license are all stored in the
portable terminal through the above process, the user can use the
DRM content.
[0008] Currently, the DRM system prevents illegal copying of the
contents distributed through a reliable network and controls the
legal usage of the contents, while maintaining confidentiality
using the license.
[0009] However, in spite of the DRM content management through
issuance of the license, a digital certificate for certifying a
qualification of a user in various transactions performed on the
web includes a routine for managing the digital certificate such
that the digital certificate can be revoked and cannot be used any
more when a particular even occurs during the use of the digital
certificate.
[0010] Contrary to the digital certificate, the license issued for
the DRM content does not include such a mechanism. Therefore, when
a contract for the digital rights between the DRM content provider
and the DRM content service provider is terminated so that the
corresponding DRM content cannot be provided any more, the
previously issued license does not include means for retrieving the
usage authority. As a result, a lot of users may maliciously use
unauthorized rights. Further, when the problems, such as the
service subscription is cancelled or the corresponding contents are
abnormally terminated, occur, the license issued for the DRM
content does not include the routine of retrieving the usage
authority of the corresponding license. Thus, it is impossible to
take the necessary measures, such as refund and usage terms
extension, for a contents buyer.
SUMMARY OF THE INVENTION
[0011] Accordingly, the present invention has been made to solve
the above-stated problems occurring in the prior art and provides
additional advantages, by providing a DRM system and a DRM method,
which can retrieve a pre-issued and usage-authority expired
license. This is achieved by providing an encrypted/decrypted key
generated through a combination of keys included in a corresponding
license of a DRM content in a system supporting a DRM content
service to a reliable user through authentication, so that it is
possible to safely protect the rights of a provider and a user of
DRM contents.
[0012] In accordance with an aspect of the present invention, a
system for managing a Digital Rights Management (DRM) content
includes: a content providing server for providing an environment,
through which a DRM content and a digital right of the DRM content
can be registered; a service providing server for issuing a license
serving as a usage authority for each of DRM content files provided
from the content providing server, generating a license revocation
execution value in a specific field of the issued license,
encrypting the generated license revocation value, and transmitting
the encrypted license revocation value to a user terminal; and the
user terminal for inspecting the license of the DRM content file
transmitted from the service providing server, and extracting and
storing the license and the license revocation execution value to
use a corresponding DRM content file according to the license, and
transmitting a revocation result of the corresponding license to
the service providing server.
[0013] In accordance with another aspect of the present invention,
a method for managing a DRM content includes: registering a DRM
content and a digital right of the DRM content; issuing a license
serving as a usage authority for each of DRM content files,
generating a license revocation execution value in a specific field
of the issued license, encrypting the generated license revocation
execution value, and transmitting the encrypted license revocation
execution value; inspecting a transmitted DRM content file, and
extracting and storing the license and the encrypted license
revocation execution value; when the usage authority of the DRM
content file has expired, generating and transmitting a license
revocation request list, in which a license ID of corresponding DRM
content file is matched with a license revocation execution code
value; and decrypting the encrypted license revocation execution
value of the corresponding DRM content file by using the revocation
code value obtained through the received license revocation request
list, and transmitting a revocation execution code key value
serving as decryption result information.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above and other aspects, features and advantages of the
present invention will be more apparent from the following detailed
description taken in conjunction with the accompanying drawings, in
which:
[0015] FIG. 1 is a diagram schematically illustrating the general
construction of a DRM content management system according to the
present invention;
[0016] FIG. 2 is a signal flowchart illustrating a signal flow
between the elements of a DRM content management system according
to a first embodiment of the present invention;
[0017] FIG. 3 is a signal flowchart illustrating a signal flow
between the elements of a DRM content management system according
to a second embodiment of the present invention; and
[0018] FIG. 4 is a flowchart illustrating a DRM content management
method according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Hereinafter, preferred embodiments of the present invention
will be described with reference to the accompanying drawings. In
the following description, the same elements will be designated by
the same reference numerals although they are shown in different
drawings. Further, various specific definitions found in the
following description are provided only to help general
understanding of the present invention, and it will be understood
by those skilled in the art that various changes in form and
details may be made therein without departing from the spirit and
scope of the invention.
[0020] While the present invention is described hereinafter with
particular reference a user terminal capable of reproducing the DRM
content, it is to be understood at the outset of the description
which follows, it is contemplated that the apparatus and methods in
accordance with the present invention may be used with terminals
capable of downloading a license from a service providing server,
and preferably to a mobile communication terminal, and other
terminals including every information and communication device and
multimedia device known to those skilled in this art, such as a
digital broadcasting terminal, a PDA (Personal Digital Assistant),
a smart phone, a 3G terminal including IMT-2000 (International
Mobile Telecommunication 2000) terminal, a WCDMA (Wideband Code
Division Multiple Access) terminal, a GSM/GPRS (Global System for
mobile Communication Packet Radio Service) terminal, a UMTS
(Universal Mobile Telecommunication Service) terminal.
[0021] Further, in the specification, the case where the digital
right of the DRM content to be described is terminated refers to a
case, in which, for example, the digital right contract between a
content providing server and a service providing server is
terminated so that the service providing server cannot provide the
user with corresponding DRM content any more, a certificate of a
user terminal capable of executing corresponding DRM content is
expired, a service subscription of the user is cancelled, or the
DRM content are determined to have a problem, such as during the
operation of an executable application program, e.g. Java contents,
a code that is maliciously added to corresponding contents during
the reproduction of the DRM content after the issuance is hidden so
that the DRM content are abnormally terminated.
[0022] FIG. 1 is a diagram schematically illustrating the general
construction of a DRM content management system according to the
present invention. Referring to FIG. 1, a brief explanation of
overall operation of the DRM content management system according to
the embodiment of the present invention will be discussed, and a
detail operation steps will be described later.
[0023] As shown in FIG. 1, the construction of the DRM content
management system of the present invention includes a content
providing server 110, a service providing server 112, and multiple
user terminals 120-1, 120-2, . . . , and 120-n. The content
providing server 110 provides an environment through which a DRM
content and a digital right of the DRM content can be registered.
The service providing server 112 issues a license serving as a
usage authority for each of DRM content files provided from the
content providing server 110, generates a revocation execution
value necessary for the revocation of the license in a specific
field of the issued license, and encrypts the generated revocation
execution value, to transmit the encrypted revocation execution
value to the multiple user terminals 120-1, 120-2, . . . , and
120-n.
[0024] Further, when the service providing server 112 receives a
digital right expiration notifying message for the specific DRM
content from the content providing server 110, the service
providing server 112 matches a license ID for each of the DRM
content files corresponding to the expired digital right with a
revocation execution code key value for decrypting the revocation
execution value generated and encrypted during the issuance of the
license, registers the matched license ID and revocation execution
code key value in a license revocation list, transmits the license
revocation list to a corresponding user terminal that has received
the DRM content file having the expired digital right, and notifies
the user terminal so as to revoke the issued license of the
corresponding DRM content file.
[0025] The multiple user terminals 120-1, 120-2, . . . , and 120-n
inspect a DRM content file transmitted from the service providing
server 112, extract and store a license and a license revocation
execution value, and then use the corresponding
[0026] DRM content file according to the license. Further, when the
multiple user terminals 120-1, 120-2, ... , and 120-n receive a
license revocation request list from the service providing server
112, the multiple user terminals 120-1, 120-2, . . . , and 120-n
identify a license ID from the received license revocation request
list and transmit a corresponding license revocation state of a DRM
content file corresponding to the identified license ID to the
service providing server 112.
[0027] In the above description, the construction of the DRM
content management system according to the embodiment of the
present invention has been schematically described. Hereinafter, a
DRM content management method according to various embodiments of
the present invention will be described in detail.
[0028] FIG. 2 is a signal flowchart illustrating a signal flow for
the operation of the DRM content management system according to a
first embodiment of the present invention.
[0029] In the following description, it is presumed that a channel
is established so as to share a license between the elements of the
DRM content management system. Further, the operation to be
described with reference to FIG. 2 illustrates an example in which
the service providing server actively requests the deletion of a
license according to the embodiment of the present invention.
[0030] Referring to FIG. 2, according to the signal flow between
the elements of the DRM content management system of the present
invention, first, the content providing server 200 providing an
environment, through which a DRM content and a digital right of the
DRM content can be registered, supply the service providing server
202 with the DRM content in step 210.
[0031] The service providing server 202 issues a license including
a license revocation execution value for each of the DRM content
files provided from the content providing server 200 and transmits
the issued license to the user terminal 204 in step 212.
[0032] More specifically, the service providing server 202 issues a
license serving as a usage authority for each of the DRM content
files provided from the content providing server 200, generates a
revocation execution value of the corresponding license in a
specific field of the issued license and encrypts the generated
revocation execution value.
[0033] At this time, the encryption of the license revocation
execution value of the DRM content file is that is, it refers to
generating of a value to be used during the revocation of the
license in a corresponding area among entire sections of a specific
DRM content file and encryption of the generated value. That is,
the encrypted value can represents a unique identification code of
a corresponding license.
[0034] As described above, when the service providing server 202
purchases DRM content file instead of the user terminal 204, the
service providing server 202 generates and encrypts a license
revocation execution value according to the set encryption
condition and issues a license including the encrypted license
revocation value.
[0035] The license clearly indicates a corresponding license
identifier (ID), the digital right for the use of the corresponding
DRM content file, a contract condition, a valid usage term,
etc.
[0036] The user terminal 204 receiving the DRM content file and the
license from the service providing server 202 inspects a specific
field, i.e. a header area, of the received license, extracts the
license and the license revocation execution value included in the
header area, and stores the extracted license and license
revocation execution value in a memory. Then, the user terminal 204
uses the corresponding DRM content file according to information
indicated in the license.
[0037] Thereafter, when the digital right for the specific DRM
content file has expired, the content providing server 200 notifies
the service providing server 202 of the digital right expiration in
step 214. Then, in step 216, the service providing server 202
matches the license ID for each of the DRM content files
corresponding to the expired digital right with a revocation
execution code key value for decrypting the revocation execution
value generated and encrypted during the issuance of the license,
registers the matched licensed ID and revocation execution code key
value in the license revocation list, and then transmits the
license revocation list to the corresponding user terminal having
received the right-expired DRM content file
[0038] The service providing server 202 checks and recognizes if
the user terminal 204 accepts or refuses the license revocation of
the corresponding DRM content file via a feedback from the user
terminal 204 with respect to the transmitted revocation request
list in step 220.
[0039] In case where the user terminal 204 has refused the license
revocation of the corresponding DRM content file, it signifies that
after transmission of the license revocation request list, the
service providing server 202 has received no feedback from the user
terminal 204 within a predetermined time period. This means that
the corresponding user terminal 204 did not decrypt the encrypted
license revocation execution value. As a result, the service
providing server 202 restricts the service of the DRM content file
in step 219.
[0040] Meanwhile, when the user terminal 204 has accepted the
license revocation of the corresponding DRM content file, the user
terminal 204 transmits a license revocation result of the
corresponding DRM content file to the service providing server 202
in step 218.
[0041] Specifically, when the user terminal 204 receives the
license revocation request list from the service providing server
202, the user terminal 204 compares the license ID registered in
the license revocation request list with a license ID stored in the
memory. As a result of the comparison, when the license ID
registered in the license revocation request list is included in
the memory, the user terminal 204 extracts a license revocation
execution value of the corresponding DRM content file stored in the
memory, decrypts the extracted license revocation execution value
by using the revocation execution code key value registered in the
license revocation request list, and transmits the revocation
execution code value serving as decryption result information to
the service providing server 202, together with the corresponding
license ID.
[0042] Further, when a specific license ID included in the
revocation request list is not included in the user terminal 204,
the user terminal 204 notifies that the specific license ID is not
included in the server.
[0043] In step 222, the service providing server 202 recognizes
that the license has been revoked through the license ID and the
revocation execution code value of the license ID transmitted from
the user terminal 204 and transmits the revocation recognition to
the content providing server 200, to notify that the license of the
corresponding DRM content file is retrieved.
[0044] Then, in step 224, the content providing server 200 grants
advantage, such as recall, refund, or usage term extension, for the
retrieved license. At this time, when the content providing server
200 receives a notification notifying that the revocation code
value of the specific license ID is not included as a response to
the revocation request, this case signifies that the license has
already expired, so that the content providing server 200 is not
required to separately refund and grant other advantages.
[0045] Next, FIG. 3 is a signal flowchart illustrating the signal
flow for the operation of the DRM content management system
according to a second embodiment of the present invention.
[0046] Further, the operation to be described with reference to
FIG. 3 according to another embodiment of the present invention
illustrates an example, in which when the service providing server
300 directly receives a request of re-issuance of the license of
the DRM content file from the user terminal 304, a new license is
issued after the revocation of a previously issued license has been
confirmed.
[0047] Referring to FIG. 3, according to the signal flow between
the elements of the DRM content management system of the present
invention, the content providing server 300 providing an
environment, through which a DRM content and a digital right of the
DRM content can be registered, provides the service providing
server 302 with the DRM content in step 310.
[0048] In step 312, the service providing server 302 issues a
license including a license revocation execution value for each of
DRM content files provided from the content providing server 300
and transmits the issued license to the user terminal 304.
[0049] More specifically, the service providing server 302 issues a
license serving as a usage authority for each of the DRM content
files provided from the content providing server 300, and generates
and encrypts a revocation execution value of the corresponding
license in a specific field of the issued license.
[0050] At this time, the encryption of the license revocation
execution value of the DRM content file is performed according to
an encryption condition set in the service providing server 302,
that is, it refers to the generation of a value to be used during
the revocation of the license in a corresponding area among entire
sections of the specific DRM content file and encryption the
generated value. That is, the encrypted license revocation
execution value can refer to a unique identification code of a
corresponding license.
[0051] As described above, when the service providing server 302
purchases DRM content file instead of the user terminal 304, the
service providing server 302 generates and encrypts a license
revocation execution value according to the set encryption
condition and issues a license including the encrypted license
revocation execution value.
[0052] The license clearly indicates a corresponding license
identifier (ID), the right for the use of the corresponding DRM
content file, a contract condition, a valid usage term, etc.
[0053] The user terminal 304 receiving the DRM content file from
the service providing server 302 inspects the received DRM content
file, extracts the license and the license revocation execution
value, stores the extracted license and license revocation
execution value in a memory, and then uses the corresponding
[0054] DRM content file according to information indicated in the
license.
[0055] At this time, the user terminal 304 periodically checks the
license of the corresponding DRM content file that have been
currently used in step 314. When the usage authority of the license
has expired as a result of the check, the user terminal 304
transmits a license re-issuance request message for the
corresponding DRM content file to the service providing server 304
in step 316.
[0056] The service providing server 302 receiving the license
re-issuance request message from the user terminal 304 generates a
revocation request list with respect to the revocation request list
in license issued for the corresponding terminal and transmits the
generated license revocation list to the corresponding user
terminal 304 requesting the license re-issuance in step 318.
[0057] The service providing server 302 checks and recognizes if
the user terminal 304 has accepted or refused the license
revocation of the corresponding DRM content file via a feedback
from the user terminal 304 with respect to the transmitted
revocation request list in step 320.
[0058] If the user terminal 304 has refused the license revocation
of the corresponding DRM content file represents the case in which
after transmission of the license revocation request list, the
service providing server 302 has received no feedback from the user
terminal 304 within a predetermined time period or notifies the
revocation refusal. Therefore, in this case, the corresponding user
terminal 304 does not decrypt the encrypted license revocation
execution value to a revocation code value. In this case, the
service providing server 302 restricts the partial service of the
DRM content file in step 319.
[0059] Otherwise, when the user terminal 304 has accepted the
license revocation of the corresponding DRM content file, the user
terminal 304 transmits a license revocation result of the
corresponding DRM content file to the service providing server 302
in step 322.
[0060] Specifically, when the user terminal 304 receives the
license revocation request list from the service providing server
302, the user terminal 304 compares the license ID registered in
the license revocation request list with a license ID stored in the
memory. As a result of the comparison, when the license ID
registered in the license revocation request list is included in
the memory, the user terminal 304 extracts a license revocation
execution value of the corresponding DRM content file stored in the
memory, decrypts the extracted license revocation execution value
by using the revocation execution code key value registered in the
license revocation request list, and transmits the revocation code
value serving as decryption result information, to the service
providing server 302, together with the corresponding license
ID.
[0061] In step 324, the service providing server 302 recognizes the
revocation of the license through the license ID and the revocation
code value of the license ID transmitted from the user terminal
302, transmits the recognized revocation to the content providing
server 300, and notifies the content providing server 300 that the
license of the corresponding DRM content file has been
retrieved.
[0062] Then, in step 326, the content providing server 300 grants
advantage, such as recall, refund, or usage term extension, for the
retrieved license. The service providing server 302 re-issues the
license for the DRM content file, of which the corresponding
license has been retrieved, in step 328.
[0063] Hereinafter, the DRM content management method by using the
DRM content management system according to the exemplary embodiment
of the present invention will be described with reference to FIG. 4
in detail.
[0064] FIG. 4 is a flowchart illustrating the DRM content
management method according to the present invention.
[0065] First, a DRM content service providing server issues a
license serving as a usage authority for each DRM content file
provided from a DRM content providing server and the DRM content
providing server includes the issued license in a specific field of
the corresponding DRM content file in step 410.
[0066] Here, the license clearly indicates a corresponding license
identifier (ID), the right for the use of the corresponding DRM
content file, a contract condition, a valid usage term, etc.
[0067] Then, in step 412, the DRM content providing server
generates a revocation execution value necessary for the revocation
of the license in a specific field of the issued license and
encrypts the generated revocation execution value, to transmit the
encrypted revocation execution value to the multiple user
terminals.
[0068] That is, the DRM content service providing server issues the
license serving as a usage authority for each DRM content file
provided from the DRM content providing server, includes the issued
license in a header area of the DRM content file, generates a
revocation execution value of the corresponding license in a
specific field of the issued license, and encrypts the generated
revocation execution value.
[0069] Here, the encryption of the license revocation execution
value of the DRM content file is performed according to an
encryption condition set by the DRM content service providing
server.
[0070] In step 414, the user terminal receiving the DRM content
file from the DRM content service providing server inspects the
specific field, i.e. the header area, of the received DRM content
file, extracts the license and a license revocation execution value
included in the header area, and stores the extracted license and
license revocation execution value in a memory. Then, the user
terminal uses the corresponding DRM content file according to
information indicated in the license in step 416.
[0071] At this time, when the digital right of the DRM content file
expires in step 418, the content providing server notifies the DRM
content service providing server of the expiration of the DRM
content file, and the DRM content service providing server matches
a license ID for each of the DRM content files corresponding to the
expired digital right with a revocation execution code key value,
which can decrypt the revocation execution value generated and
encrypted during the issuance of the license, registers the matched
license ID and revocation execution code key value in a license
revocation list, and then transmits the license revocation list to
the corresponding user terminal that has received the digital
right-expired DRM content file in step 420.
[0072] After the performance of step 420, the DRM content service
providing server checks and recognizes if the user terminal has
accepted or refused the license revocation of the corresponding DRM
content file through feedback transmission from the user terminal
with respect to the transmitted revocation request list in step
423.
[0073] First, when the user terminal refuses the license revocation
of the corresponding DRM content file, the DRM content service
providing server has received no feedback from the user terminal
within a predetermined time period after step 420, in which the DRM
content service providing server transmits the license revocation
request list to the user terminal, and thus the corresponding user
terminal has not decrypt the encrypted license revocation execution
value to a revocation code value. Therefore, in this case, the DRM
content service providing server restricts the service of the
corresponding DRM content file in step 425.
[0074] In contrast, when the user terminal accepts the license
revocation of the corresponding DRM content file, the user terminal
compares a license ID registered in the license revocation request
list with a license ID stored in a memory. After the comparison,
when the license ID registered in the license revocation request
list is included in the license ID stored in the memory, the user
terminal extracts a license revocation execution value of the
corresponding DRM content file stored in the memory and decrypts
the extracted license revocation execution value by using the
revocation execution code key value registered in the license
revocation request list in step 422.
[0075] Then, the user terminal transmits a revocation code value
serving as decryption result information, to the DRM content
service providing server, together with the corresponding license
ID in step 424.
[0076] As a result of the check in step 421, when the DRM content
service providing server has received the feedback from the user
terminal, the service providing server recognizes that the license
has been revoked through the license ID and the revocation code
value of the license ID transmitted from the user terminal,
transmits the recognized license revocation to the DRM content
providing server, and notifies the retrieval of the license of the
corresponding DRM content file. Consequently, the DRM content
providing server grants advantage, such as recall, refund, or usage
term extension, for the retrieved license in step 426.
[0077] In the meantime, according to another embodiment of the
present invention, the checking of the digital right expiration
performed in step 418 can be performed through directly and
periodically checking the license of the currently used
corresponding DRM content file by the user' terminal, not through
the DRM content service providing server from the DRM content
providing server. When the usage authority of the license has
expired as a result of the check, the user terminal transmits a
re-issuance request message for the license of the corresponding
DRM content file to the DRM content service providing server. Then,
after identically performing steps 420 through 426, the DRM content
service providing server re-issues the license of the DRM content
file, of which the corresponding license has been retrieved.
[0078] According to the present invention, through providing the
encrypted/decrypted key of the keys included in the license of the
DRM content file, the present invention can induce the revocation
of the previously issued license having the expired usage
authority, and confirms the license revocation, so that it is
possible to efficiently manage the DRM content. Further, the
present invention can grant the advantage, such as refund and usage
term extension, for the corresponding DRM content of the revoked
license, so that the present invention can provide the DRM content
purchaser with the reliable service.
[0079] Further, when the corresponding license of the DRM content
is attacked from a malicious user so that the inappropriate
operation, such as the indiscreet issuance of the corresponding
license is incurred, the present invention can retrieve the
pre-issued license, so that it is possible to efficiently and
stably provide the DRM content service.
[0080] Through the above description, it is possible to implement
the system and the method for the DRM content management. While the
present invention has been shown and described with reference to
certain exemplary embodiments and drawings thereof, it will be
understood by those skilled in the art that various changes in form
and details may be made therein without departing from the spirit
and scope of the invention as defined by the appended claims.
[0081] Note that the above-described methods according to the
present invention can be realized in hardware or as software or
computer code that can be stored in a recording medium such as a CD
ROM, an RAM, a floppy disk, a hard disk, or a magneto-optical disk
or downloaded over a network, so that the methods described herein
can be executed by such software using a general purpose computer,
or a special processor or in programmable or dedicated hardware,
such as an ASIC or FPGA. As would be understood in the art, the
computer, the processor or the programmable hardware include memory
components, e.g., RAM, ROM, Flash, etc. that may store or receive
software or computer code that when accessed and executed by the
computer, processor or hardware implement the processing methods
described herein.
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